Retinal ganglion cells of cat have been divided into three classes on the basis of a constellation of features, primarily those of dendritic morphology, cell body size, dendritic stratification and dendritic field diameter. The bipolar and amacrine inputs to some of these cells have been studied by serial section electron microscopy. Such cells have also been subdivided into types a and b depending upon whether dendrites ramify in the outer 1/3 of the inner plexiform layer (IPL) (sublamina "a": the domain of "flat" cone bipolar terminals) or the inner 2/3 of the IPL (sublamina "b": the domain of "invaginating" cone bipolar terminals). Members of classes I and II, strictly follow this bisublaminar organization of the IPL, and can always be assigned to types a or b, as can the majority of class III cells. Comparison of types Ia and Ib, with OFF-center and ON-center "brisk-transient" cells of Cleland and Levick (1974), indicated that sublamina a conveyed OFF-center properties and sublamina b ON-center properties to ganglion cells through parallel cone bipolar pathways. We have substantiated this hypothesis by iontophoretic staining of ganglion cells with fluorescent dyes after intracellular recording.